One teenager was killed and 20 others were injured after at least three shooters opened fire during an unauthorized gathering in Washington, authorities said.

Washington Mayor Muriel Bowser at a press conference said that the gathering violated the city’s coronavirus-induced ban on public meetings of more than 50 people.

“There were certainly was too many people out there, you know, with the COVID-19. We can’t tolerate these types of gatherings in our city during COVID-19. It’s just too dangerous,” D.C. Metropolitan Police Chief Peter Newsham said.